Device to assist the performance of a heart

ABSTRACT

A device to assist the performance of a heart with at least one pump that is formed as a rotary pump and driven via a magneto coupling.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims the benefit of priorityto U.S. application Ser. No. 18/308,958 filed on Apr. 28, 2023, which isa continuation of and claims priority to U.S. application Ser. No.18/087,083 filed on Dec. 22, 2022 (now U.S. Pat. No. 11,674,517), whichis a continuation of and claims priority to U.S. application Ser. No.17/446,046 filed on Aug. 26, 2021 (now U.S. Pat. No. 11,572,879), whichis a continuation of U.S. application Ser. No. 16/282,948 filed on Feb.22, 2019 (now U.S. Pat. No. 11,123,540), which is a continuation of U.S.application Ser. No. 14/454,965 filed on Aug. 8, 2014 (now U.S. Pat. No.10,251,984), which is a continuation of U.S. application Ser. No.13/555,318 filed on Jul. 23, 2012 (now U.S. Pat. No. 8,801,590), whichis a divisional of U.S. application Ser. No. 12/449,632 filed on Aug.18, 2009 (now U.S. Pat. No. 8,255,050), which is the U.S. national phaseof International Application PCT/IB2008/000421 filed on Feb. 27, 2008,which designated the U.S. and claims benefit of AT A 306/2007 filed Feb.27, 2007, the entire contents of these prior applications are herebyincorporated by reference.

BACKGROUND

After a heart failure, for example a cardiac infarction or other reasonsfor the decrease in the performance of a heart, it is of essentialimportance for intensive care medicine to normalise and stabilise thecardiac function again as rapidly as possible. When for example thevolume output of the heart is distinctly reduced as a result of afailure, it is particularly important to reliably and rapidlyre-establish a corresponding peripheral blood flow in order to preventsecondary damage. The use of heart-lung machines basically allows theessential vital functions to be maintained. A specific adaptation to therespective actual requirements generally does not take place with suchdevices, however. Rather, conventional heart-lung machines are deviceswhich, using external pumps, maintain a forced circulation of bloodwithout systematically entering into the respective requirements of theheart which has been weakened or subjected to a failure.

In surgical interventions, particularly in the vein area, it has alreadybeen proposed to carry out retroinfusion, controlled by venous pressure,from or in veins of the body with the suction” of fluid and return ofthe fluid via a pump. Conventional catheters are used here, the luminaof which allow a suction of fluid and via the lumina of which the returnis made possible at a suitable site. Known devices, particularly for theretroinfusion of blood in coronary veins in the area of myocardialprotection during a brief coronary artery closure within a cardiologicalintervention, are generally devised so that a balloon dilatation of anarteriosclerotically constricted coronary artery is carried out. Inthese cases, a compensation which is adapted to the intervention brieflytaking place respectively can be carried out by the return of bloodwhich has been drawn off in veins. For a continuous restitution of thefull function of a heart, however, the criteria are not taken intoaccount which would be relevant for the full function of the heart, andan intensive provision over a particular period of time is therefore notprovided with such devices. At the same time, the provision of the otherorgans must also be maintained.

In the device known from AT 407 960 B for assisting the performance of aheart, fluid is removed from blood vessels via an external pump and isreturned into blood vessels via a return catheter, in which the returnedquantity of fluid is regulated as a function of measurement values, witha heart ventricle catheter being provided to obtain these measurementvalues. The known device comprised a heart ventricle catheter which isequipped in the cardiac chamber with sensors to measure the volume offluid per unit of time, in which these sensors, in the introduced stateof the heart ventricle catheter, lie in the cardiac chamber and thesesensors are connected with an evaluation circuit in which the ratio ofthe diastolic volume to the systolic volume is evaluated per heartbeator per unit of time in particular the discharge rate and/or thedeviation of the volume conveyed per unit of time by the heart from adefined rated value is evaluated, for example the rated value,calculated from physically specific data for the cardiac output. Thesignal which is generated in this way is passed to the pump, via whichfluid is withdrawn from the cardiac chamber and is recirculated as afunction of the generated signal.

SUMMARY

A fluid flow which is improved by the pump is to be developed in a wayin which the mechanical stress of highly sensitive fluids, such as bloodfor example, can be kept as low as possible and nevertheless thecorresponding improvement to circulation can be ensured at desiredlocations. A completely impervious separation of the rotor from thedrive wheel is achieved by a magneto coupling which is providedaccording to the invention, which eliminates axial passages between thedrive wheel and the rotor lying distally on the outside.

The rotor itself can follow design principles such as described forexample in WO 01/70300 A1. The rotary pump shown and described there forconveying blood and other highly sensitive fluids is formed as anexternal electromagnetically driven pump which is not directly suitablefor incorporation into a catheter. However, for the desired conveyingcapacity with the axial pump according to the invention, provision isalso made according to the invention that the rotor has guide surfacesto produce centrifugal flow components.

The driving fluid can be used within the scope of the invention in orderto be able to operate a balloon for retroperfusion. The embodiment ispreferably devised hereby so that the lumina for the driving fluid areguided through an expandable balloon surrounding the catheter in asealing manner, and that the lumina have separately controllable closuremembers via which driving fluid can arrive in the balloon or out of theballoon into the respective lumina, in which preferably the closuremembers are formed as magneto valves. On inflation of the balloon,additional driving medium is required which can be discharged again oncollapsing of the balloon. This is possible extracorporally on the driveside by means of a reservoir.

The embodiment to assist the performance of a heart according to theinvention, in which fluid is conveyed in blood vessels with the use of apump and the conveyed quantity is able to be regulated as a function ofmeasurement values of a heart ventricle catheter, from which the cardiacoutput is determined, proceeds from a development according to AT 407960 B and is characterised substantially in that the pump is formed asan intravasal rotary pump at the periphery or at the distal end of thecatheter, the rotor of which, lying on the outside, is connected via amagneto coupling with the drive which is arranged inside the catheter.

BRIEF DESCRIPTION OF DRAWINGS

The invention is explained in further detail below by use of anexamplary embodiment which is illustrated diagrammatically in thedrawings, in which FIG. 1 shows a diagrammatic illustration of thearrangement of the pump and of the drive, FIG. 2 shows a diagrammaticillustration of the distal end of a catheter which is used according tothe invention, and FIG. 3 shows an enlarged illustration of the part ofthe catheter bearing the balloon, in section.

DETAILED DESCRIPTION

In FIG. 1 , a heart is designated by 1, into which a heart ventriclecatheter 2 is introduced. The catheter is introduced here for examplevia the femoral artery and the aortic arch 3 into the heart chamber andcarries a series of sensors 4 via which the volume can be determined.The measurement signals are passed to a control arrangement 5. The heartventricle catheter is formed with several lumina, as additionallyillustrated below in further figures of the drawings, with fluid beingsupplied via such lumina to drive a rotor, arranged at the distal end,which forms the pump to assist the blood circulation and is designatedby 6 in FIG. 1 . The positioning of this rotor is indicated in FIG. 1 bythe arrow 8. The driving medium for the rotor or the pump is guided in acircular flow by means of a fluid pump 7 which can be regulated in asynchronised manner as a function of the control signals generated inthe control arrangement 5. The distal region in which the pump isarranged is designated diagrammatically by 8, the catheter 2 having atits distal end a tube 9 leading to the suction end 10. A reservoir fordriving fluid is designated by 11, which provides additional drivingmedium for filling the balloon 12 serving for an occlusion of theartery, and which receives again the volume of driving medium occurringon deflation of the balloon.

The volumetric measurement in the cardiac chamber allows differences tobe reliably detected between the diastolic and systolic volume andallows corresponding correction signals to be made available for theoutput of the synchronised fluid pump 7.

Furthermore, in the control circuit 5, corresponding fixed values can beprovided, such as for example a defined cardiac output, which isreferred to on deviation of the measured cardiac output to control thepump.

A retroperfusion can take place via a conventional balloon catheterwhich is occluded in a correspondingly synchronized manner, so that thedirected return is in fact guaranteed during the diastole. Hereby thecorresponding measurement values for the heart rate or for the correctmoment of the diastole can be obtained from ECG data.

In FIG. 2 , the distal end of a modified catheter 2 is now illustrated.The end side 13 of this catheter has two pocket-shaped chambers 14 and15, in which bar magnets are respectively arranged. The bar magnet 16 isconnected here at the distal end outwards via a shaft 17 with a rotor18, whereas the bar magnet 19 lying on the inside is connected via ashaft 20 with a drive wheel 21. The drive wheel 21 is formed here as apaddle wheel and is acted upon with fluid via a lumen 22, this fluidflowing off again via the lumen 23 of the catheter. The rotation of thepaddle wheel 21 is regulated here accordingly by corresponding controlof the fluid pressure in the lumen 22 serving for the supply of fluid,in which the magnet 19, which is connected so as to be locked againstrelative rotation with the paddle wheel 21, is set into correspondingrotation. At the outer side, which is completely sealed with respect tothe lumina 22 and 23, the magnet 16 is subsequently entrainedaccordingly and drives the rotor 18 via the shaft 17, whereby a flow isformed in the region of the tube 9, as is indicated by the arrows 24,and which assists the natural blood flow in the vessel 26, illustratedby the arrow 25.

In FIG. 3 , the partial region of the balloon 12, which is connected ina sealing manner to the catheter 2, is illustrated on an enlarged scale.The two lumina leading away from the fluid pump 7 and back to the fluidpump 7 are designated in turn by 22 and 23. In the region of the balloon12, the wall of these lumina is provided with valves which can beactuated magnetically for example. The valves are indicateddiagrammatically by 27 and 28. An opening of the valve 27 leads to thefluid, coming from the fluid pump 7, which is under pressure, which isindicated by the “+” sign, being pumped into the balloon 12, with whichthe overall quantity of the circulating driving fluid would of course bereduced, in so far as the reservoir 11, indicated diagrammatically inFIG. 1 , is not provided. By closing the valve 27, the occlusion isclosed off, the collapsing of the balloon 12 being able to be broughtabout by opening the valve 28 and the fluid now being drawn off via thelumen 23, leading back to the pump, which lumen 23 is at a slightlylower pressure which is indicated by the “−” sign. As the overall volumeof the fluid in the circulating system is now to be reduced, a portionof this volume must be pumped back again into the reservoir 11 accordingto FIG. 1 .

1. A system for assisting the blood circulation of a heart, comprising: a heart assist pump device deliverable to the heart and comprising: an inflow tube defining a blood inflow path and having a suction end insertable into a ventricle of the heart; a magnetically driven rotor axially aligned with the inflow tube and being spaced apart from the suction end when the suction end of the inflow tube is inserted into the ventricle, the magnetically driven rotor being rotatable within a surrounding rotor housing to act upon blood flowing from the inflow tube toward the rotor, the magnetically driven rotor being rotatable about a central axis and being rigidly coupled to and axially adjacent to a first magnetic device that is located within the surrounding rotor housing; a second magnetic device axially aligned with the inflow tube and positioned to magnetically drive rotation of the magnetically driven rotor via a magneto coupling with the first magnetic device while being spaced apart and sealed from both the magnetically driven rotor and the first magnetic device by at least one sealing wall, the second magnetic device being positioned axially spaced apart from the magnetically driven rotor; a blood outflow port positioned radially adjacent the magnetically driven rotor such that blood driven by the magnetically driven rotor is configured to exit the surrounding rotor housing in a direction transverse to the central axis of the magnetically driven rotor, wherein when the magnetically driven rotor is rotated, the magnetically driven rotor remains adjacent to and spaced apart from the surrounding rotor housing by the blood flowing from the inflow tube and to the blood outflow port; and an external control unit configured to regulate operation of the second magnetic device, wherein the external control unit is connectable to the heart assist pump device for controlling the second magnetic device to thereby magnetically drive the rotation of the magnetically driven rotor via the magneto coupling with the first magnetic device. 